Aircraft parts are typically fastened to aircraft structure or base with fasteners. Often gaskets, including pliable, sticky polyurethane gaskets, such as those found in U.S. Pat. Nos. 6,530,577; 6,695,320; and 7,229,516, incorporated herein by reference are used. During compression of the gasket as the workpiece is fastened down with torque applied to fasteners, there is sometimes squeeze out laterally at or near a perimeter edge of the gasket. Sometimes the perimeter edge of the gasket generally conforms in shape to the perimeter of the part that is being fastened to the base. However, once the workpiece is fastened, there is sometimes further squeeze out or sometimes there is actually an indentation where there was not sufficient gasket material (in an undercut gasket) to carry out to the edge of the perimeter of the workpiece, leaving the indentation. Sometimes the tightening or torque down on the fasteners, which generates squeeze out of a pliable gasket body, brings the deformable gasket body right up to the workpiece perimeter, but usually squeeze out extends beyond the perimeter.
It may be advantageous, for aesthetic and functional reasons (as in providing a good environmental seal and limiting squeeze out), to provide a perimeter seal, that may be shaped, that contacts and surrounds substantially all of the perimeter of the part, the gasket body that may or may not have been squeezed out past the perimeter of the part or the workpiece, and the base upon which the workpiece is to be fastened.